1. Field of the Invention
The present invention relates generally to an apparatus, system, and method for parsing incoming data traffic, and specifically to an apparatus, system, and method for parsing incoming time division multiplexed (TDM) data traffic before reconstructing the originally transmitted data packets.
2. Description of the Related Art
In a conventional data communication system, a network controller performs many functions including parsing incoming data to identify instructions or commands. The data is then processed in accordance with those instructions or commands. In a data communication system in which multiple incoming channels are being received, the network controller must receive the data packets on each of these channels and then parse the received packets to determine what to do with them, e.g., where to forward the packets, in what order the packets should be reassembled, etc. Thus, the received packets must be stored in memory while the network controller reconstructs the originally transmitted packets and then determines what to do with them.
An exemplary data communication system is conceptually illustrated in FIG. 1. The different components in FIG. 1 should be understood as functional modules, which can be combined or further divided as necessary for implementing a particular embodiment.
In FIG. 1, a Network Controller 50 receives and transmits data traffic between a Wide Area Network (WAN) 110 and Local Area Network (LAN) 130. WAN 110 covers a large amount of addressable processors and/or a large geographic area, and can be understood as, for example, the Internet which uses IP/TCP (Internet Protocol/Transmission Control Protocol) communications links, or a Public Switched Telephone Network (PSTN). LAN 130 covers a smaller amount of addressable processors and/or a smaller geographical area, and can be understood as, for example, a bus-based network (e.g., Ethernet, IEEE 802.3), a ring-based network (e.g., Fiber Distributed Data Interface or Token Ring), or a tree-based or star-based network.
Communication link 105 connects WAN 110 with LAN 130 under control of Network Controller 50. Data traffic is received in a time division multiplexed (TDM) format, where different channels occupy different time slots. How this is done depends on the nature of the communications link (e.g., a T1 or E1 carrier) and/or the particular protocol used (e.g., Frame Relay). Although the network controller shown here is located between a WAN and a LAN, it should be understood that the present invention, as described hereinbelow, can apply to any device performing the activities of a network controller, regardless of the type, or types, of network to which the device is connected, the protocols used therein, or the transmission media on which the data traffic is carried.
Network Controller 50 processes this incoming data stream in order to properly route, unpack, and identify the communications units, e.g., packets, bundles, frames, etc. For example, Network Controller 50 must identify the arriving bytes as belonging to a particular channel, and/or as belonging to a particular larger communications unit, etc. To accomplish this, Network Controller 50 must store arriving bytes to form larger communication units, such as packets. This is further complicated by the fact that the individual bits are arriving on different TDM channels, so that they need to be separated into different waiting queues for grouping into larger communication units (e.g., packets). Another layer of complication is added when connectionless packets (such as IP/TCP packets from the Internet) are received on a channel, because these packets can arrive in any order, thus requiring the network controller to not only reassemble the individual packets, but to also wait for out-of-order packets, and put them in the correct order.
Thus, the network controller spends an inordinate amount of time waiting for bytes and larger communication units, such as packets or a series of packet fragments, to form from the individual bits arriving on each channel. Furthermore, certain control and organization information stored in particular locations within a communication unit (e.g., the header in a data packet) will not be parsed by the network controller until the communication unit has completely formed, further adding to delay and wasted resources (i.e., for some of the data, no processing occurs, only storing and reassembling, for multiple clock cycles). It is only after this initial data link processing that the incoming packets can be brought up through the higher layers of the communication protocol stack, e.g., the TCP/IP protocol stack.
In order to reduce the delays caused by this initial data link processing, conventional network controllers or interfaces have added dedicated hardware to the data path to perform the initial data link processing. This added hardware relieves the main processor of the network controller of the initial processing, thereby allowing the main processor to focus on higher level processing. Because one of the main functions of such added hardware is to identify flows and parse data packets, it is sometimes called a “packet parser”.
However, prior art packet parsers are typically limited to specific protocols, and/or types of networks. This lack of flexibility is further compounded by the fact that typical packet parsers are “hard-wired” to perform particular tasks (e.g., serial-to-parallel conversion, identifying flows to which a packet belongs, authenticating packets, decrypting packets, forwarding packets to memory buffers, etc.). There is no possibility of providing different processing for packets on different channels. Furthermore, typical packet parsers slow down the incoming data flow in order to perform their parsing function. Further still, typical packet parsers are completely unsuited for receiving TDM data traffic, where the incoming data stream jumps from channel to channel, resulting in bytes from different channels (and, thusly, different packets) arriving at substantially the same time.
Therefore, there is a need for an apparatus, system, and method by which data traffic received on multiple channels in a TDM data stream can be efficiently parsed or pre-processed. Furthermore, there is a need for an apparatus, system, and method for parsing and/or pre-processing an incoming multi-channel TDM data stream without slowing down the incoming data flow.